Process of making solid bodies from nitrids



UNITED v sTArps PATENT OFFIGE.

"Emu, ronszus, or rnnrrow, NEAR snnnrn, GERMANY, Assreuoa, .BY mnsm:ASSIGN- HENTS, TO THE CHEMICAL FOUNDATION, INC., A. CORPORATION OFDELAWARE.

PROCESS OF MAKING SOLID BODIES FROM NITBIDS.

No Drawing. Application filed October 21, 1914, Serial No. 867,888.Renewed June 26, Hi9, Serial No. 866,880ik.

To all whom it may concern." Be it known that I, Erma Ponszos, a'citizenof the German Empire, residing at Treptow, near Berlin, Germany, have1nvent ed certain new and useful mprovements in the Processes of MahngSolid Bodies from Nitride; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it ap-- which have no melting pointunder ordinary pressure and are sublimated.wl1en heated. Therefore ithas not been possible to shape such substances into solid bodies of anydesired form, which would be desir-' able in view of various well knownproperties of the substances, particularl of the boron nitrid. Theobject of the improvements is to provide a process whereby substancesofthe class indicated can be fritted together into solid bodies of anydesired form.-- 'With this object in view my invention consists'in firstshaping bodies of the desired form from such compounds as may form thebasis elements of the substances,

for example from compounds of boron, ti-

"fritted ifnecessary in an oxidizing atmosphere. When glowing in ammoniais continued slowly and long enough, the bodies are transformed intouniform and'solid nitrid bodies. In some cases, for example when glowingtitanium nitrid, the bodies show cracks, which however is avoided bysubjecting the material such as the oxid to a preliminary baking ormelting process at a sufliciently high temperature. By my improvedprocess niti'id bodies are obtained which are almost impermeable togases. However where large bodies must be transformed the processrequires much time, be-

cause the action of the ammonia is slow by reason of the slow diffusion.Therefore my improved process is particularly useful, where the bodiesto be produced are comparatively thin and consist for example of thintubes, threads, and the like, in which cases bodies are produced whichare durable and uniform.

In a preferred modification of the process I do not use as startingsubstances exclusively the oxid or other suitable compound of the basismaterial, but I add thereto the nitrid which is uniformly mixed with thecompound, the amount of the latter being sufficient to bind the wholemass into a coherent mass by melting or fritting. This process isparticularly advisable when producing boron-nitrid, because from purebolow temperature, a bod of boron nitrid can not easily be obtaine Amass of, oxid which is uniformly distributed is obtained by partialoxidation of the pure nitrid, for

example by forming from the nitrid and a suitable organic binding mediumas is commonly used as binders in sintering processes bodies of thedesired form, and burning therefrom the binding medium.

By the same process bodies of mixtures of nitrids and' other substances,such as tungsten and other metals. can beproduced, by admixing the saidsubstances with the starting material, for example with the oxid.

In order that the invention be more clearly understood, 1 shall nowdescribe by way of example the manufacture of a body of boron nitrid.

From finely ground boron nitrid and a sufiicient amount of a suitableorganic binding medium a plastic mass is made and treated in a Wetstate, until a sufficient amount of boric acid has been formed. Ifdesired the boric acid may be added to the boron nitrid together withthe binding medium, in which case however the amount should not betoolarge. The plastic mass is now brought into the desired form anddried, whereupon it is liberated from the organic binding mediumpreferably in an oxidizing atmosphere, whereby the bo-ric Specificationof Letters Patent. Patented Apr. 29, 1920,

- ron trioxid which melts at a comparatively acid is fritted and cementsthe particles of boron nitrid together. Thereupon the formed body isslowly glowed in a current 'of ammoma, so that gradually a body of boronnitrid is produced. In order to render the said body more dense -Iprefer to imbibe the same with lycer l borate or molten boron trioxidand to g ow the same once more. Thereby a body of high density isobtained.

Bodies which have thus been produced are suitable for numerous purposes,particularly where high temperatures are required, and in a reducingatmosphere, because the boron nitrid which is thus produced isdiss'ociated at a temperature of not less than 2000 degrees centigradeand is Sublimated in a current of hydrogen only at a temperature whichis even higher, while in a current of ammonia and nitrogen it isrefractory even at higher temperatures, for example in an atmosphere ofnitrogen at a temperature of 3000 degrees centigrade. Therefore whenused as a material for constructing furnaces it is superior to all thematerials which have heretofore been used for this purpose, so much themore as the material is also electrically insulating at the. highesttemperatures and is not affected by changes in the temperature.Furthermore it is important as a substance for making crucibles formelting metal, because even boiling alkali metals have no injuriouseffect on the same.

Objects of titanium nitrid are made in a similar way, byfinely grindinga burnt or molten oxid, addmga suitable organic binding mediumsufficient to form a paste or plastic mass and bringing the same in thedesired form, and burning the same in an oxidizing flame and thereafterin ammonla, or directly in ammonia. In th1s process the 01nd 1s at firstfritted together and is thereaftertransformed into the nitrid. If it isdesired to mixthe same. with a 'metal such as tungsten, the metalis'admixed with the oxid' and the whole mass is burnt in ammonia. Amodification of the process consists in making a 7 solid body. from thebasis element of the nitrid, and transforming the same into the nitrid.

I claimherein as my invention:

1. The hereindescribed process of making solid nitrid bodies, whichcomprises shapin or forming a body of a frittable compound capable ofbeing transformed into nitrid, havinghigh heat resisting properties,while maintaining its form, fritting or sintering the body, andthereafter converting the fritted or sintered and shaped body intonitrid.

2. The hereindescribed process of making solid nitrid bodies, whichcomprises shaping or forminga body of afrittable compound capable ofbeing transformed into nitrid, having high heat resisting properties,while maintaining its form, fritting or sintering the body andthereafter converting the fritted or sintered and shaped body intonitrid by heating the same in an atmosphere ofv ammoma.

I 3. The hereindescribed process of making solid nitrid bodies havinghigh heat resisting properties, which comprises shaping or forming abody of a mixture of nitrid and a frittable compound capable of beingtransformed into nitrid while maintaining its form, fritting orsintering the compound and thereafter converting the fritted or sin--tered compound into nitrid;

4. The hereindescribed process of making solid nitrid bodies, whichcomprises shaping or forming a body of afrittable compound capable ofbeing transformed into nitrid, having high heat resisting properties,while maintaining its form, fritting or sintering the body, andthereafter converting the fritted or ,sintered and shaped body intonitrid, imbibing the body with a compound capable of being transformedinto nitrid, and transforming the imbibed compound into nitrid.

' 5. The-hereindescribed process of'making solid nitrid bodies havinghigh heat resisting properties, which comprises shaping or forming abody of a frittable compound capable of being transformed into nitridmixed with a metal also capable of being transformed into a nitrid,fritting or sintering the body and then converting the mixture whileretaining its shape into nitrid.

- forming the fritted shaped body into nitrid.

7. The hereindescribed process of making solid nitrid bodies having highheat resisting properties, which comprises subjecting a compound capableof being transformed .into nitrid to melting, shaping and forming theground resulting product, fritting the formed body and then transformingit into nitrid in a nitrogen containing gas.

8. The hereindescribed process of making solid nitrid bodies, whichcomprises shaping or formin a body of a frittable compound capable 0being transformed into nitrid rendered'plastic with a carbonizable andoxidizable binder, fritting the body so formed and simultaneouslyeliminating the binder, and then heating the body in an atmosphere ofammonia at a temperature sufiicient to convert the compound into nitrid.

In testimony whereof I hereunto afiix my signature in the presence oftwo witnesses.

, EMIL PODSZUS.

Witnesses: c

HENRY HASPER, WOLDEMAR HAUPT.

